Coastal Lake-Sediment Records of Prehistoric Hurricane Strikes in Honduras and Turks and Caicos Islands of the Caribbean Basin

by Knowles, Jason Thomas

Abstract (Summary)

This study seeks to apply the geological method of paleotempestology to reconstruct past hurricane activities for Central America and the Caribbean. Landfalling hurricanes may deposit distinct overwash sand layers in coastal lake sediments through storm surges and tidal overwash processes that can be dated to establish a chronology of past hurricane strikes. Proxy records from lake-sediment cores were taken for this study in the spring and summer of 2003 from Lake Sophie, Providenciales Island, Turks and Caicos, and from Laguna de Los Micos, Honduras. Loss-on-ignition analysis revealed many changes in the sediment stratigraphies for both sites that appear to represent overwash sand layers caused by past hurricane landfalls. The identification of the overwash sand layers through loss-on-ignition and grain size analyses and radiocarbon dating allowed for a preliminary estimation of return periods and annual landfall probabilities for the regions around Laguna de Los Micos and Lake Sophie. Four cores taken from Laguna de Los Micos, composed mostly of gyttja, contain two distinct sand layers deposited within 500 years of sediment. Radiocarbon dating indicates that the events occurred around AD 1660 and 1550, suggesting a return period of 250 years and an annual landfall probability of 0.4% for Laguna de Los Micos. The core from Lake Sophie is composed of marl and contains 8 distinctive layers of coarse calcareous sand that are interpreted to be hurricane overwash layers. Radiocarbon dating indicates the core to be around 4240 years old, suggesting a return period of 530 years and an annual landfall probability of 0.18% for Lake Sophie. The return periods and annual landfall probability estimates for these sites in Honduras and Turks and Caicos Islands were found to be comparable to those reported from the U.S. Gulf Coast. These results are the first proxy records of past hurricane strikes for Central America and the Caribbean region.